Synchronous motors. A synchronous engine is one in which the rotor normally rotates at the same velocity as the revolving field in the device. The Leaf Chain stator is similar to that of an induction machine consisting of a cylindrical iron framework with windings, generally three-phase, located in slots around the inner periphery.
usually, synchronous motors are used for applications where precise and continuous speed is required. Low power applications of the motors include positioning devices. These are also applied in robot actuators. Ball mills, clocks, record participant turntables also make use of synchronous motors.
The principle of operation of a synchronous motor could be understood by considering the stator windings to be connected to a three-phase alternating-current supply. The effect of the stator current is definitely to establish a magnetic field rotating 
at 120 f/p revolutions each and every minute for a frequency of f hertz and for p poles. A direct current in a p-pole field winding on the rotor may also create a magnetic field rotating at rotor acceleration. If the rotor swiftness is made equal to that of the stator field and there is no load torque, both of these magnetic fields will have a tendency to align with one another. As mechanical load is usually applied, the rotor slips back again several degrees with respect to the rotating field of the stator, developing torque and ongoing to end up being drawn around by this rotating field. The angle between the fields improves as load torque is definitely increased. The utmost available torque is accomplished when the angle where the rotor field lags the stator field can be 90°. Application of more load torque will stall the motor.
One advantage of the synchronous electric motor is usually that the magnetic field of the machine can be made by the immediate current in the field winding, to ensure that the stator windings need to provide just a power component of current in phase with the applied stator voltage-i.e., the electric motor can operate at unity power element. This condition minimizes the losses and heating system in the stator windings.